Backup kit for a patient-specific arthroplasty kit assembly

ABSTRACT

A method for preparing a backup kit for a plurality of patient-specific arthroplasty procedures scheduled at the same medical facility includes providing a database with data from completed arthroplasty procedures using patient-specific arthroplasty kits. The database includes comparisons between preoperatively planned implant size and intraoperatively implanted implant size. The method includes determining a statistically expected implant size deviation from a planned implant size for each implant included in a plurality of patient-specific arthroplasty kits prepared for a shipment to the medical facility using the database. A backup kit of backup implants is assembled for the shipment. The number and size of the backup implants is determined from the statistically expected implant size deviations.

INTRODUCTION

The present teachings provide a backup kit including backup arthroplasty implants for a shipment of a plurality of patient-specific arthroplasty kits for a plurality of corresponding arthroplasty procedures at the same medical facility. The patient-specific arthroplasty kits generally include patient-specific alignment guides, custom and non-custom implants and other instruments for use during an arthroplasty procedure. The patient-specific alignment guides (and patient-specific implants, when used) are designed and constructed preoperatively based on three-dimensional digital images of the patient's joint that is scheduled to undergo arthroplasty. The digital images of the patient's joint can be reconstructed from medical scans of the patient using commercially available CAD (Computer Aided Design) and/or other imaging software.

SUMMARY

The present teachings provide a method for preparing a backup kit for a shipment of patient-specific arthroplasty kits for corresponding arthroplasty procedures scheduled at the same medical facility. The method includes providing a database with data from completed arthroplasty procedures that were performed using patient-specific arthroplasty kits. The database includes comparisons between preoperatively planned implant size and intraoperatively implanted (actual) implant size. A statistically expected implant size deviation from a planned implant size for each implant included in the shipment is determined using the database. A backup kit of backup implants is assembled for the shipment. The number and size of the backup implants is determined from the statistically expected implant size deviations.

The present teachings also provide a backup kit for a plurality of patient-specific arthroplasty procedures scheduled at the same medical facility. The backup kit includes a plurality of backup implants selected for a shipment of a plurality of patient-specific arthroplasty kits for the medical facility. Each patient-specific arthroplasty kit is configured for corresponding arthroplasty procedures at the same medical facility. The number and size of the backup implants is determined from statistically expected implant size deviations from planned implant sizes in the corresponding arthroplasty kits using a compliance database. The compliance database includes data from completed arthroplasty procedures performed using patient-specific arthroplasty kits. The compliance database includes comparisons between preoperatively planned implant sizes and intraoperatively implanted implant sizes.

Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic view of an exemplary patient-specific arthroplasty kit;

FIG. 2 is a schematic view of a shipment of a plurality of patient-specific arthroplasty kits similar to the patient-specific arthroplasty kit of FIG. 1 according to the present teachings;

FIG. 3 is a schematic view of a backup kit for the shipment of FIG. 2 according to the present teachings;

FIG. 4 is a flowchart for a method according to the present teachings; and

FIG. 5 is an exemplary partial listing of a compliance database according to the present teachings.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF VARIOUS ASPECTS

The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses. For example, although some of the present teachings are illustrated for a knee implant, the present teachings can be used for any orthopedic implant.

The present teachings provide a backup kit that includes backup arthroplasty implants for a shipment of a plurality of patient-specific arthroplasty kits for use at the same medical facility for a plurality of corresponding arthroplasty procedures. The patient-specific arthroplasty kits generally include patient-specific guides, custom and non-custom implants and other instruments for use during an arthroplasty procedure such as, for example, cutting guides, drill guides, cutting blocks, fixation pins, etc. The patient-specific guides and/or patient-specific implants, if used, are designed and constructed preoperatively based on three-dimensional digital images of the patient's joint that is scheduled to undergo arthroplasty. The backup kit includes backup implants of various sizes to be included with each particular shipment. The number and sizes of the backup implants in the backup kit are determined from a statistical analysis of patient-outcomes that are stored in a compliance database, as discussed below.

Generally, patient-specific devices including implants and/or patient-specific alignment guides, resection guides or other instruments can be designed preoperatively using computer-assisted imaging methods. Three-dimensional digital images of the patient's joint anatomy can be reconstructed from MRI, CT, ultrasound, X-ray, or other medical scans of the patient's anatomy. Various CAD programs and/or other software can be utilized for three-dimensional digital image reconstruction, such as, for example, software commercially available from Materialise USA, Plymouth, Mich.

Various pre-operative planning methods and patient-specific devices are disclosed in commonly assigned U.S. patent application Ser. No. 11/756,057, filed May 31, 2007, U.S. patent application Ser. No. 11/971,390, filed on Jan. 9, 2008, U.S. patent application Ser. No. 12/025,414, filed on Feb. 4, 2008, U.S. patent application Ser. No. 12/039,849, filed Feb. 29, 2008; U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008; U.S. patent application Ser. No. 12/103,824, filed Apr. 16, 2008; U.S. patent application Ser. No. 12/371,096, filed Feb. 13, 2009, U.S. patent application Ser. No. 12/483,807, filed Jun. 12, 2009; U.S. patent application Ser. No. 12/872,663, filed Aug. 31, 2010, U.S. patent application Ser. No. 12/973,214, filed Dec. 20, 2010, and U.S. patent application Ser. No. 12/978,069, filed Dec. 23, 2010. The disclosures of the above patent applications are incorporated herein by reference.

In the preoperative planning stage for an arthroplasty procedure, a preoperative surgical plan is formulated for a specific patient with interactive input from the patient's surgeon or other medical professional. Imaging data of the relevant joint anatomy of a patient can be obtained at a medical facility or doctor's office using any of the medical imaging methods described above. The imaging data can include, for example, various medical scans of a relevant joint portion or other relevant portion of the patient's anatomy, as needed for joint or other anatomy modeling and, optionally, for determination of an implant alignment axis or for other alignment purposes. The imaging data thus obtained and other associated information can be used to construct a three-dimensional computer (digital) image of the joint or other portion of the anatomy of the patient, such as, the hip joint, knee joint, etc. The three-dimensional digital image of the patient's anatomy is also used to formulate a preoperative surgical plan for the patient including, for example, location and orientation of resections, removal of osteophytes or other protrusions, mechanical alignment, deformity correction, ligament balancing, or other preoperative planned procedures The preoperative surgical plan can also include the design and construction of patient-specific alignment guides, resection guides or other patient-specific instruments, and, optionally, the design and construction of patient-specific implants. Further, the preoperative surgical plan can include the determination and selection of particular sizes of non-custom implants, digital images of which can be viewed and compared relative to the three-dimensional digital image of the patient's anatomy on a digital display.

Generally, the patient-specific devices, whether implants or instruments, are configured to match at least a portion of a joint anatomy of a specific patient and are generally designed and configured using computer modeling based on the patient's reconstructed three-dimensional digital image of the patient's corresponding joint anatomy. Each patient-specific device includes a three-dimensional patient-specific surface that is configured to conformingly contact and match a corresponding surface of the patient (with or without cartilage or other soft tissue), using the reconstructed three-dimensional digital image of the patient's anatomy and the computer methods discussed above. In this respect, a patient-specific device can register and nestingly mate with the corresponding bone surface (with or without articular cartilage) of the specific patient in only one position.

The three-dimensional digital model of the patient's anatomy can be viewed on a computer display or other electronic screen and can also be reproduced as a hard copy on film or other medium and viewed by direct or indirect or backlight illumination. The digital model can be sized for viewing on any appropriate screen size (including handheld mobile devices, such as smart phones, PDAs or tablets) and may be cropped, rotated, etc., as selected by the individual (e.g., the surgeon) viewing the screen.

The surgeon's review of the surgical plan may include implant selection, and/or a request for one or more patient-specific instruments, such as alignment guides, resection guides or other instruments to be used with the selected implant. The patient-specific devices can be manufactured by rapid prototyping methods, such as stereolithography or other similar methods or by CNC milling, or other automated or computer-controlled machining or robotic methods. The patient-specific instruments, the selected implants and optionally other disposable instruments can be sterilized, assembled in a patient-specific kit and forwarded to the surgeon or the surgeon's medical facility for implantation. The selected implants can be non-custom implants of a size determined and approved by the surgeon in the preoperative plan for the patient.

Many medical facilities (or surgeons) place orders requesting multiple patient-specific kits for use by the same or different surgeons at the same facility for procedures scheduled for the same day or a few days apart. Referring to FIG. 2, an omnibus patient-specific kit assembly 200 can include a plurality of patient-specific arthroplasty kits 100 (100A, 100B, 100C, etc.) for shipment to a single medical facility. Each patient-specific arthroplasty kit 100A, 100B, 100C can be labeled with the patient's name or identification number (ID), such as A, B, C, the corresponding surgeon's name, X, Y, Z and the side of the joint for the procedure, R or L for right or left, for example, or other information. Additionally, each patient-specific component in each patient-specific arthroplasty kit can also be labeled with the patient's name, the joint side, etc.

The present teachings provide a method to design and prepare a backup kit 300 (see FIG. 3) for an entire bulk order or shipment that includes several patient-specific arthroplasty kits, as discussed below. Accordingly, the present teachings reduce weight, expense and unnecessary backup implant components for each patient-specific kit while providing the surgeon(s) and or the facility with sufficient oversize or undersize implants for the totality of the procedures, rather than for each single procedure. The determination of the number and size of additional or backup implants to be included in the backup kit 300 is made using statistical analysis of the size outcomes previous procedures which are stored in a compliance database, as described below. Duplicate size backup implants can also be included.

An exemplary patient-specific arthroplasty kit 100 for a knee procedure is shown in FIG. 1. It will be appreciated that similar kits can be prepared for other joints, such as the hip joint, shoulder joint or other joints. The patient-specific arthroplasty kit 100 can include, for example, a patient-specific femoral alignment guide 110, a patient-specific tibial alignment guide 118, a femoral drill guide 112, a tibial drill guide 120, a femoral distal cutting block 114, a tibial cutting block 130, a four-in-one femoral cutting block 116, and a tibial template 122. The patient-specific alignment guides 110, 118 are single-use guides and disposable. Detailed description of the patient-specific alignment guides and associated methods can be found in the patent applications referenced above (and incorporated by reference herein). The various drill guides and cutting blocks can be re-sterilzable and reusable, although disposable drill guides, cutting blocks and other tools can also be designed. Additionally, a set of trochar pins 132 and a set of spring drill pins 134 can be included. Depending on the surgeon's preferences, additional tools and/or medical products and supplies can be included, such as cutting blades, bone cement, biologics, etc.

The patient-specific arthroplasty kit 100 can include a set of arthroplasty implants, such as, for example, a femoral implant 150, a bearing 152 and a tibial implant 154, for an exemplary total knee arthroplasty procedure, or other implant components depending on the surgical procedure and the surgeon's preference. The arthroplasty implants can be either patient-specific or non-custom implants. Semi-custom arthroplasty implants, i.e., implants including some patient-specific features and some standard, non-custom features can also be used, as described, for example, in commonly assigned U.S. patent application Ser. No. 12/872,663, filed Aug. 31, 2010, referenced above (and incorporated by reference herein).

Referring to FIGS. 1-3, the implants or implant components 150, 152, 154 included in each patient-specific arthroplasty kit 100 can be non-custom components of a size selected during the preoperative plan for the patient. Predominantly, the selected or planned implant size is found to be a match and no change in implant size is required intraoperatively. For the few cases that the implant-size is found intraoperatively, for various reasons, not to be the best match, a best match implant can be found in the preoperatively prepared backup kit 300 with a degree of a built-in or preoperatively determined degree probability, using a compliance database 500, as discussed below. The backup kit 300 can include a predetermined number of backup implant components. For illustration purposes only, three different sizes for each implant component 150, 152, 154 are shown in the single backup kit 300 that accompanies the patient-specific kit assembly 200. The selection of number and sizes the implant components to be included in the backup kit is discussed below with reference to FIGS. 4 and 5.

An exemplary (but not necessary representative) portion of a compliance database 500 is illustrated in FIG. 5. The compliance database 500 can be generated from information collected for each arthroplasty procedure for which a patient-specific arthroplasty kit was provided. The compliance database 500 can include the planned implant size, as well as the actual implant size that was eventually used. Information collected and provided by the database 500 can also include date of the procedure, patient Identification, surgeon name, the side (R right, L left) for the procedure and other characteristics of the patient, such as, for example, weight, ethnicity or race, gender, age or other characteristics that may be of significance in selecting implant size or that can be factors for a size deviation or mismatch.

The number of procedures scheduled for the same date can vary, the norm being several procedures per day, although a single procedure or eleven or twelve procedures in a single day are not uncommon. In the exemplary illustration of FIG. 5, the implant sizes presented are for a femoral component 150 of the Vanguard® Knee Complete System, commercially available from Biomet Manufacturing Corp., Warsaw, Ind. The available sizes correspond to mediolateral (ML) dimensions of the femur in mm. The interval between sizes for the Vanguard® Knee, for example, is 2.5 mm for sizes ranging from size 55 to size 75. A size 80 mm is also available. Similarly, nine sizes are available for the tibial component 154 and seven sizes for the bearing 152 for the Vanguard® Knee. Implanting the wrong size, i.e., implant mis-sizing for the femoral implant 150 can result in excessive mediolateral overhang, especially in women, and can cause over-tightening of the knee capsule when a larger size is used. Providing backup sizes (one size larger or one size smaller than a planned size) for each and every implant in the shipment to the same facility can be costly, wasteful and inefficient both in bulk and weight. The compliance database 500 can be created and used to reduce the number of backup implants for the shipment, while still providing a high probability that the intraoperatively determined implant size is the planned size or is included in the backup kit.

The partial data presented chronologically in FIG. 5 may be somewhat misleading in that they show a higher proportion of mismatches between planned and actual implant sizes than is the case when all the available data is considered for a longer period of time. For example, Applicant's data for a period ranging from Dec. 1, 2008 to Jun. 19, 2009 can be summarized as follows: 54 mismatches or implant size deviations for a total of 397 arthroplasty procedures, or a 13.8% ( 54/398) mismatch (or deviation) rate. From the 54 mismatches, in 44 mismatches the planned size was oversized (one size too big; rate 44/397=0.11) and in 11 mismatches the planned size was undersized (one size too small; rate 11/397=0.28). It is noted, however, that, according to the present teachings, the compliance database 500 is updated frequently or for each procedure performed, and that the contents of the backup kit 300 can then be determined by statistical analysis of the updated compliance database 500. For example, if N patient-specific arthroplasty kits 100 are required for a single day D in a medical facility M, and each patient-specific arthroplasty kit 100 includes one implant of the type 150 (femoral knee component), then the database is analyzed to determine the proportion of higher and lower sizes that may be needed for a set of N implants of type 150 and having a particular size. The statistical analysis, in its simplest form, may be based on percentages, or may include other considerations, such as reduction of mismatches over time as the technology evolves, patient characteristics, surgeon preferences, various weighing factors and other parameters. The statistical analysis can also include a specified contingency or probability coverage, i.e., what percentage of all mismatch cases should be covered, such as, for example from 98% or higher. Error analysis, standard deviation analysis, data reliability analysis and other statistical methods and algorithms known in the art can also be considered in the calculations. It is also noted that the compliance database 500 can depend on the characteristics of the implants and instruments used and can, therefore, vary from manufacturer to manufacturer. Accordingly, a relevant compliance database 500 can be generated or otherwise available to be accessed for determining the backup kit for a particular manufacturer according to the present teachings.

As an illustration, the surgical schedule for the date Dec. 8, 2008 includes two R (right side) components of size 70 and three R components of size 67.5. For these five components, based on the 11% chance of oversize determined from the compliance database 500, one backup implant of size R67.5 for planned implant size R70 and one backup implant of size R65 for planned size R67.5 may be provided in the backup kit 300. Duplicative backup implants (backup implant has same size as planned implant size) can also be included in the backup kit 300 to account for loss of sterilization, mishandling or other mishaps and accidents at the medical facility. The number of duplicative backup implants can be determined from statistical analysis of data included in the compliance database 500, or from other historical records or databases, or from surgeon and/or medical facility preferences and requirements.

In some embodiments, the backup kit 300 may be prepared for all the arthroplasty procedures performed at the same medical facility M for a different period of time, a week, for example. For the week of Dec. 1, 2008 to Dec. 5, 2008, for example, five L67.5 implants were planned. One backup implant of size L65 can be included in the backup kit based on the 11% rate of oversize mismatch. If the undersize mismatch rate is only 2.8%, as in data presented above, a separate backup kit 300 that includes bigger sizes for the lower chance of undersize planned implants may be maintained at facility M to be accessed as needed and replenished periodically. A backup kit with larger sizes for undersize planned implants can be prepared, for example, using estimates based on anticipated needs for longer periods of time, such as, per month, quarterly, etc. Further, the rate of mismatch can be calculated from the database for each particular size. For example, if the rate of oversize mismatch is x % for a particular implant size N, then for every hundred implants of size N (in mm) in one shipment (a patient-specific kit assembly 200) of patient-specific arthroplasty kits 100, an x number of implants of one size lower than N, i.e., N-2.5, can be included in the backup kit 300. If only ten implants are included in the backup kit 300, then x/10 implants of the smaller size are included in the backup kit 300. The statistically determined number of backup implants for each planned implant size in the shipment (or patient-specific kit assembly) 200 of patient-specific arthroplasty kits 100 is not necessarily an integer and can be rounded up or down to the nearest integer number.

It will be appreciated that other backup implants can be included in the backup kit 300, above and beyond those that can be statistically required. For example, a surgeon may require a larger size backup implant for any planned size below 60 mm. Such considerations can be used to modify the backup kit 300 after the backup implant components have been determined by statistical analysis. In some cases, the contents determined by statistical analysis may already satisfy the surgeon's or the medical facility's additional requirements.

Referring to FIG. 4, a flowchart of a method of assembling a backup kit 300 according to the present teachings is illustrated. At block 400 a compliance database 500 is created or otherwise provided for access. At block 402, an omnibus patient-specific kit assembly or shipment 200 is prepared for a facility M. As discussed above, the patient-specific kit assembly 200 includes a plurality of patient-specific arthroplasty kits 100 that are scheduled to be performed on the same day or within a specified number of days, such as, for example, on the same forthcoming week. The sizes of the various implants of the patient-specific kit assembly 200 and corresponding patient-characteristic can be identified at block 404. A statistical analysis can be performed at block 406 to determine the likelihood of deviation or mismatch between preoperatively planned implant sizes and actual implant sizes as predicted by the compliance database 500. Based on the results of the statistical analysis, expected deviations in implant size, i.e., the number of planned implants expected to be oversized or undersized can be determined at block 408 and a backup kit of implants can then be assembled at block 410. The compliance database 500 can be updated at 412 with data from the new arthroplasty procedures that have been performed.

As discussed above, a compliance database 500 of preoperatively planned and actual (intraoperatively selected) implants can be created from data collected from patient-specific preoperative plans and actual arthroplasty usage. The database provides details of mismatches or deviations between a planned implant size and an actually used implant size. The information in the database can be statistically analyzed to help determine the number and sizes of extra of backup implants to be included in a backup kit 300 for a plurality of arthroplasty procedures that are planned preoperatively and include patient-specific arthroplasty kits 100.

Example embodiments are provided so that this disclosure is thorough, and fully conveys the scope to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure.

It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Accordingly, individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A backup system for a patient-specific arthroplasty procedure, the system comprising: a plurality of implants, one or more of the plurality of implants having a size that differs from a preoperatively planned size of another of the plurality of implants that are part of the backup system, an amount and sizes of the plurality of implants determined from a statistically expected implant size deviation from the preoperatively planned size and determined using a database having data from completed arthroplasty procedures with other patient-specific arthroplasty systems, the database including comparisons between preoperatively planned implant sizes and intraoperatively implanted implant sizes.
 2. They system of claim 1, wherein the one or more of the plurality of implants comprise are designed to be used instead of the preoperatively planned size of the another of the plurality of implants should the another of the plurality of implants not fit properly.
 3. The system of claim 1, wherein the sizes of the one or more of the plurality of implants differ from the preoperatively planned size of the another of the plurality of implants by an interval of 2.5 mm.
 4. The system of claim 1, further comprising a patient-specific alignment guide.
 5. The system of claim 4, wherein the patient-specific alignment guide comprises a patient-specific knee alignment guide.
 6. The system of claim 5, wherein the backup system includes at least a non-custom femoral implant, a non-custom tibial bearing component and a non-custom tibial implant, and wherein at least one of the plurality of implants includes any one of the non-custom femoral implant, the non-custom tibial bearing component and the non-custom tibial implant.
 7. A backup system for a patient-specific arthroplasty procedure, the system comprising: a database of data from completed arthroplasty procedures using prior used patient-specific arthroplasty systems, information collected and provided by the database including comparisons between a plurality of preoperatively planned implant sizes and a plurality of intraoperatively implanted implant sizes, the database being updated after patient-specific arthroplasty procedures are performed and depending upon characteristics of implants and instruments used in the patient-specific arthroplasty procedures; a plurality of implants assembled for a shipment to a medical facility by accessing and referencing the database; and a computer configured to determine a statistically expected implant size deviation from a preoperatively planned implant size using the database; wherein an amount and sizes of the plurality of implants for the backup system are determined from the statistically expected implant size deviation from the preoperatively planned implant size.
 8. The system of claim 7, wherein the database is updated with intraoperatively implanted implant size for each patient-specific procedure after the arthroplasty procedure is completed.
 9. The system of claim 7, further comprising a patient-specific alignment guide included with the plurality of implants for the shipment.
 10. The system of claim 7, wherein the backup system includes at least one non-custom implant.
 11. The system of claim 7, wherein the size of at least one of the plurality of implants differs by a size interval of 2.5 mm from the preoperatively planned implant size.
 12. The system of claim 7, wherein the computer is configured to determine a quotient of a rate of mismatch divided by a number of the plurality of implants corresponding to the plurality of implant sizes.
 13. The system of claim 7, wherein the computer is configured to determine a proportion of the plurality of implants having larger and smaller sizes than the preoperatively planned implant size based on a rate of mismatch and a number of the plurality of implants corresponding to the plurality of implant sizes.
 14. The system of claim 13, wherein the rate of mismatch includes a rate of oversized mismatch and a rate of undersized mismatch.
 15. The system of claim 7, wherein the statistically expected size deviation includes an oversized deviation and an undersized deviation.
 16. The system of claim 7, wherein the amounts and sizes of the plurality of implants are determined based on a percentage of mismatch cases to be accounted for.
 17. The system of claim 7, wherein the backup system includes at least a non-custom femoral implant, a non-custom tibial bearing component and a non-custom tibial implant, and wherein at least one of the plurality of implants includes any one of the non-custom femoral implant, the non-custom tibial bearing component and the non-custom tibial implant. 